The true depths of these stunning Moroccan caves are unknown.

World's largest film studio, where visitors tour the decaying sets that litter the harsh desert environment.

A fortified city, home to a remaining population of five families

Founded as a refugee camp, now a popular tourist spot.

Crumbling necropolis set high above Fez.

The other side is actually green.

Morocco's largest Jewish cemetery.

Mosaics, storks, and brothels—this ancient city has it all.

An eerie former warehouse turned cistern turned movie set.

A 12th-century fortress containing some of Berlin's oldest buildings.

Beneath the impressive baroque cathedral that rises from the center of Berlin lies the largest collection of Prussian royals in the world.

Berlin's oldest surviving academic architecture hosted decades of animal dissections.

The abandoned remains of this Victorian brewery hide crumbling bowling alleys and rusting industrial gear.

Man-made mineral caves house massive bat colony.

This old Estonian mine has been kept like a sprawling time capsule of the local shale industry.

A miniatures park with a model of Wolf's Lair as it looked during World War II.

A peculiar family mausoleum built by a German nobleman captivated by the occult.

This wooden recreation of a 9th century lake village looks as though it was built yesterday (which it relatively was).

Boats must transform into railroad cars to navigate this Polish canal.

An old hill fort covered in over 100,000 crosses is a symbol of Lithuanian nationalism and beliefs.

This insurance company building reminds customers that witches, bears, and gnomes are out there, best be insured.

A subterranean house of worship carved right out of the bedrock.

An abstract monument to a symphonic composer.

This disappearing geyser has been attributed to witchcraft, but really it's all about rainfall.